1. Field of Endeavor
The present invention relates to analysis of nucleic acids and more particularly to analysis of nucleic acids using signal enhancement with a switchable magnetic trap.
2. State of Technology
Microfluidic devices are poised to revolutionize environmental, chemical, biological, medical, and pharmaceutical detectors and diagnostics. “Microfluidic devices” loosely describes the new generation of instruments that mix, react, count, fractionate, detect, and characterize complex gaseous or liquid-solvated samples in a micro-optical-electro-mechanical system (MOEMS) circuit manufactured through standard semiconductor lithography techniques. These techniques allow mass production at low cost as compared to previous benchtop hardware. The applications for MOEMS devices are numerous, and as diverse as they are complex.
As sample volumes decrease, reagent costs plummet, reactions proceed faster and more efficiently, and device customization is more easily realized. By reducing the reaction volume, detection of target molecules occurs faster through improved sensor signal to noise ratio over large, cumbersome systems. However, current MOEMS fluidic systems may only be scratching the surface of their true performance limits as new techniques multiply their sensitivity by ten, a hundred, or even a thousand times.
The present invention provides a system for enhancing a microfluidic detector's limits by magnetically focusing the target analytes to be detected in an optical convergence zone until interrogation has been performed. The present invention provides an additional reduction of costly reagent volumes over standard MOEMS systems, since much fewer targeted reactions are needed to produce a detectable signal. This not only provides the desirable cost incentive, but can cut processing times by an order of magnitude, making many popular on-chip process, such as Polymerase Chain Reaction (PCR) truly real time.
The present invention provides a method for performing sample wash steps in-line to cleanse the sample of unwanted reaction by-products, change the buffered pH, introduce new or next-step reagents, and remove excess or previous-step reagents from the reaction and detection zones. This opens the door to multi-step sequential reactions occurring while the target molecules or complexes are held within detection and imaging zone.
The present invention has many uses in different technology fields. For example, the present invention has use in the following situations: Biowarfare detection applications: identifying, detecting, and monitoring bio-threat agents that contain nucleic acid signatures, such as spores, bacteria, and viruses; Biomedical applications: Tracking, identifying, and monitoring outbreaks of infectious disease including emerging, previously unidentified and genetically engineered pathogens; Automated processing, amplification, and detection of host or microbial and viral DNA or RNA in biological fluids for medical purposes; Automated processing and detection of proteomic signatures in biological fluids; Cell cytometry or viral cytometry in fluids drawn from clinical or veterinary patients for subsequent analysis; and High throughput genetic screening for drug discovery and novel therapeutics; Forensic applications: Automated processing, amplification, and detection DNA in biological fluids for forensic purposes; and Food and Beverage Safety: Automated food testing for bacterial or viral contamination.